METHOD FOR AUTOMATICALLY ADJUSTING AUDIO RESPONSE FOR IMPROVED INTELLIGIBILITY

Description

BACKGROUND

[0001] The present invention relates generally to radio receivers and, more particularly, to an apparatus and method for dynamically altering the audio response of a radio receiver to improve intelligibility of received speech.

[0002] In documents US-A-5 450 494 and EP-A-669 711 there are disclosed sound reproductions systems (such as auto radios and the like) that have maintaining sound quality (fidelity) as an important goal. In US-A-5 450 494, a controller controls the gain by which amplifiers amplify signals sent from the sound producing apparatus to speakers based on the ambient noise level. For example, when the volume of ambient noise increases, the controller merely increases the gain correspondingly. US-A-5 450 494 thus basically relates to a volume control apparatus although frequency range selective amplification may be involved. As explained, document EP-A-669 711 is similarly related to a device wherein sound quality is an important goal.

[0003] In particular, EP-A-669 711 discloses the features of the introducing portion of Claim 1 including feature c), and US-A-5 450 494 discloses a similar apparatus comprsirig means for determining an ambient noise level, a controller, and a digital signal processor, as specified in Claim 14.

[0004] Mobile and portable radios are often used in areas with high ambient noise which degrades the intelligibility of transmitted and received messages. The use of noise canceling microphones addresses the issue of impaired transmissions, but there is little a user can do to overcome ambient noise while receiving the audio signals except to increase the received volume or wear a headset.

[0005] Both of these approaches have limited usefulness. That is, there is a limit to the total audio energy the radio is capable of producing without severe distortion, especially with portable receivers. In addition, increasing the volume adds to the pre-existing high ambient noise level, which could result in other noise sources increasing their volume, thereby further aggravating the problem. Headset pose problems with comfort, and the attenuation of ambient noise may cause safety problems for the wearer.

[0006] Some manufacturers of consumer audio equipment have included a "loudness" control in their radio receivers. While this does select between preset audio response curves, it is a manual operation left to the user.

SUMMARY OF THE INVENTION

[0007] It is therefore a main object of the present invention to provide a method and apparatus wherein an audio response is automatically adjusted to improve intelligibility in areas with high ambient noise, thereby overcoming the problems of the prior art, i.e. to provide a method and apparatus for dynamically altering the audio response of a radio receiver to yield the best tradeeffbetween "naturalness" and intelligibility of received speech.

[0008] "Naturalness" conceptually refers to the natural frequencies of generated sound. In this regard, a "natural" audio response includes no enhancement of any frequencies so that the outputted signal response more closely corresponds to the input signal.

[0009] In general, a basic concept of the invention is to increase the relative gain of the higher audio frequencies at the expense of low frequency response to improve intelligibility when there is high ambient noise. The decision on when to boost the high frequency gain can be based on sampled ambient noise or on the user's choice of received volume setting. (In the latter case, a high setting would be taken as an indicator that ambient noise is also high.) Under high ambient noise levels, some "naturalness" is traded for the higher intelligibility provided by increased high frequency gain.

[0010] This object of the invention is solved by the attached independent claims. Further advantageous embodiments are disclosed in the dependent claims.

[0011] According to one aspect of the present invention there is provided a method of dynamically altering an audio response of an audio portion of a radio receiver whereby to improve the intelligibility of received speech in areas of high ambient noise, comprising the steps of:

a) determining an ambient noise level;

b) determining in the audio portion an audio response function corresponding to the determined ambient noise level; and

c) adjusting the audio response of the audio portion of the radio receiver in accordance with the audio response function,

and wherein when the ambient noise level increases to such an extent that the intelligibility of received speech is adversely affected, the determined audio response function serves to increase the gain of high audio frequencies of the audio response relative to the gain of low audio frequencies of the audio response, thereby improving the intelligibility of received speech albeit with a loss of fidelity of a speaker's voice.

[0012] Step (b) may be practiced by building an audio response message for a digital signal processor (DSP) or by modifying a response of a dedicated filter circuit.

[0013] In preferred forms, step (a) may be practiced by detecting a volume knob position or by sampling the ambient noise level using a microphone input. In each instance, step (b) is preferably practiced by accessing an array of audio parameters and selecting parameters corresponding to the volume knob position or the sampled ambient noise level, respectively.

[0014] The method may further include dividing a receive audio passband into at least low frequency and high frequency sub bands to define an array of audio parameters corresponding to each volume knob position or a range of ambient noise levels. In this regard, step (b) is preferably practiced by accessing the array of audio parameters and selecting parameters corresponding to the volume knob position or sampled ambient noise level.

[0015] Prior to step (c), the method may further include sending the audio response message to a DSP, wherein step (c) is carried out by the DSP. Further, the method may include, also prior to step (c), extracting audio response parameters from the audio response message and substituting the audio response parameters into a DSP filter routine.
According to another aspect of the present invention there is provided an apparatus for dynamically altering an audio response of an audio portion of a radio receiver whereby to improve the intelligibility of received speech in areas of high ambient noise, the apparatus comprising:

means for determining an ambient noise level;

a controller that builds an audio response message, in accordance with ambient noise level, and

a digital signal processor that adjusts the audio response of the audio portion of the radio receiver in accordance with the audio response message, and wherein when the ambient noise level increases to such an extent that the intelligibility of received speech is adversely affected, the audio response message serves to increase the gain of high audio frequencies of the audio response relative to the gain of low audio frequencies of the audio response, thereby improving the intelligibility of received speech albeit with a loss of fidelity of a speaker's voice.

[0016] By virtue of the present invention, no adjustment is required by the operator, especially when controlled by sampling ambient noise directly.
Moreover, the "naturalness" of received speech is only compromised when necessary to enhance intelligibility, thus received audio will be unaltered during normal ambient noise conditions. Still further, by limiting the energy of the low frequencies, the volume of the high frequencies can be raised substantially beyond the point where distortion would normally limit usable volume.

BRIEF DESCRIPTION OF THE DRAWINGS

[0017] These and other aspects and advantages of the invention will become more clear in view of the following detailed description of the preferred embodiments when read in conjunction with the accompanying drawings in which:

FIGURE 1 is a block diagram showing the hardware configuration of a portable radio;

FIGURE 2 is a flow chart of the control microprocessor implementation according to the invention;

FIGURE 3 is a graph illustrating electronic communication concepts according to the present invention; and

FIGURE 4 is a flow chart of the digital signal processor (DSP) implementation according to the invention.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

[0018] FIGURE 1 is a block diagram showing the hardware configuration of a portable radio such as the Ericsson Prism (HP) portable radio manufactured and sold by Ericsson, Inc. of Lynchburg, Virginia. Those of ordinary skill in the art will contemplate other structural configurations to carry out the method according to the invention, and the invention is not meant to be limited to the illustrated portable radio. The structure illustrated in FIGURE 1 is merely one example of a hardware configuration that is compatible with the features of the present invention.

[0019] Referring to FIGURE 1, the portable radio 10 includes a microprocessor 12, which serves as the primary controller for the radio. The microprocessor 12 monitors inputs provided from the user control inputs 14. The user control inputs 14 encompasses user controls such as PTT, volume control and the channel selector. An EEPROM 16 holds information that personalizes the product to the user's needs. This information can include the operating frequencies, group ID's, operator preferences and the like. A flash memory 18 also communicates with the microprocessor 12 and stores program information for the microprocessor and personality information similar to that held in the EEPROM. The flash memory may also contain operational software to be downloaded to the digital signal processor (DSP) 20 (described below). The display 22 is typically an LCD indicator used to display current selections and radio status.

[0020] The DSP 20 is responsible for all audio processing and assumes part of the role of the modem. The demodulator function is provided by the DSP 20, and all audio filtering is done with the DSP 20. A digitized microphone audio input 22 communicates with the DSP 20, wherein the microphone audio has already been digitized by a CODEC or equivalent. A digitized receiver I.F. input 24 also communicates with the DSP, wherein the receiver intermediate frequency signal is fed to a phase digitizer and then sampled directly by the DSP 20. A digitized TX modulation output to synthesizer is the transmit audio, which is routed to the transmitter synthesizer in digital form. In this particular configuration, conversion to analog audio is not necessary. Finally, a digital RX audio output 28 (for speaker audio) is also provided, which is the digital audio destined for the speaker. It is converted to analog audio by an external CODEC prior to being fed to an audio power amplifier (not shown).

[0021] The detailed structure of the portable radio is well known to those of ordinary skill in the art, and the details of the structure illustrated in FIGURE 1 will therefore not be further described.

[0022] FIGURES 2 and 4 illustrate the process performed by the microprocessor 12 of the portable radio 10. FIGURE 2 illustrates the process executed as part of the background task performed periodically by the microprocessor 12. During this background task, the microprocessor examines the input controls to detect user activity, such as button presses and knobs being turned, and determines a level of ambient noise for determining an audio response function. With the DSP 20, the audio response function is determined by building a corresponding audio response message. As an alternative to the DSP 20, a dedicated analog filter circuit (not shown) may be provided. In this regard, the audio response function would be determined by modifying a response of the dedicated filter circuit.

[0023] In accordance with the present invention, the ambient noise level is first examined in step S101. If the ambient noise level is found not to have changed at all or not enough to constitute a change (no in step S102), then the microprocessor 12 skips ahead to step S105, and no action is taken. However, if a new ambient noise level is detected (yes in step S102), the microprocessor fetches audio parameters for the new level from the personality storage (either EEPROM or flash memory) (step S103). In step S104, these parameters are assembled into a message, which is then sent to the DSP 20.

[0024] The ambient noise level checked in step S101 is determined in accordance with either the volume setting (determined by the position of the volume knob) or a direct sampling of ambient noise using the digitized microphone audio input 22. With respect to determining the volume setting, it is assumed that a high volume setting is indicative of a high ambient noise level. The microprocessor accesses an audio parameter table including the audio parameters stored in the EEPROM 16 and/or flash memory 18 in accordance with the volume setting or the sampled ambient noise level.

[0025] The definition of the audio parameter table is derived from fundamental electronic communication concepts. FIGURE 3 illustrates important concepts according to the present invention. Curve "b" demonstrates the effect on articulation efficiency caused by setting the lower cutoff frequency at various points. Typical mobile radio systems use a lower cutoff frequency of 300 Hz, which yields an articulation efficiency of nearly 100%. Curve "b" shows that raising this lower cutoff frequency to as high as 1000Hz causes only a small decrease in articulation efficiency, to 90%. Curve "d" shows the total sound energy as a function of lower cutoff frequency. It can be seen that moving the lower cutoff frequency up to 1000 Hz causes a major reduction in the total sound energy. As noted above, curve "b" provides that this can be accomplished with minimal effect on articulation efficiency.

[0026] Raising the cutoff frequency thus lowers the contribution to total energy caused by the lower frequency speech components, while having a small effect on articulation efficiency. The advantage is that the reduction in energy allows greater amplification to be applied to the higher frequencies, which convey most of the intelligence of human speech. The trade off is the "naturalness" of the speech. Since uneven amplification is applied to various bands of audio frequencies, there is a loss of fidelity of the speaker's voice.

[0027] A possible data structure for the audio parameters is shown below. In this arrangement, there is an array that contains a row for each possible volume setting. If the ambient noise level is determined using a direct sampling of ambient noise, a similar array would be accessed containing a row for each of a selected range of ambient noise levels. (For ease of discussion in this example, it is assumed that the volume is adjustable over eight steps. A radio would typically have 32 or more selectable levels.) Each row contains a boost/buck (positive/negative gain) setting for each sub band of the receive audio. In this example, the receive audio pass band is divided into low frequency, mid frequency, and high frequency sub bands. The boost/buck value indicates the gain relative to the default audio response curve. With this set of data, mid and high frequencies would receive relative boosts at volume settings of 5 and greater, and low frequency gain will be reduced.

VOLUME SETTING	LOW FREQUENCY	MID FREQUENCY	HIGH FREQUENCY
1	0	0	0
2	0	0	0
3	0	0	0
4	0	0	0
5	-1	0	+1
6	-2	0	+2
7	-3	-1	+3
8	-4	-2	+3

[0028] Note that this chart illustrates a particular implementation of the invention. In this case, the audio curve shaping is based on the volume setting, which is assumed to be indicative of ambient noise conditions where the transmission is being received. As noted above, sampled ambient noise could alternatively be used to access the personality storage.

[0029] FIGURE 4 details the DSP algorithm that processes messages from the microprocessor and, in particular, the DSP software that responds to the audio response message. In the same fashion as the microprocessor, the DSP has a list of background tasks that are performed on a regular schedule. One such task is to check for and process messages from the microprocessor. If no messages are present (no in step S201), the processor skips ahead to step S205 and the task is finished. However, if a message is present (yes in step S201), the message type field is examined in step S202. Messages other than the audio response message are handled in software sections not detailed here (no in step S202). When an audio response message is received (yes in step S202), the new audio response parameters are extracted from the message in step S203. In step S204, these new parameters are substituted into the DSP audio filter routines. These routines may be already in use, such as the case when the radio is receiving a call. Alternatively, if the filter routine is not currently in use, the new parameters will be used when the filter routine is next begun. The process then proceeds to step S205 and the task is finished.

[0030] As illustrated in the chart described above, as the ambient noise level increases, which is either detected by an increase in volume level or a microphone sampled ambient noise, the relative gain of the higher audio frequencies is increased at the expense of low frequency response to improve intelligibility. Of course, the "naturalness" of received speech is only compromised when necessary to enhance intelligibility, and thus, received audio will be unaltered during normal ambient noise conditions. In addition, by limiting the energy of the low frequencies, the volume of the high frequencies can be raised substantially beyond a point where distortion would normally limit usable volume.

[0031] While the invention has been described in connection with what is presently considered to be the most practical and preferred embodiments, it is to be understood that the invention is not to be limited to the disclosed embodiments, but on the contrary, is intended to cover various modifications and equivalent arrangements included within the scope of the appended claims.

Claims

1. A method of dynamically altering an audio response of an audio portion (20-28) of a radio receiver (10) whereby to improve the intelligibility of received speech in areas of high ambient noise, comparing the steps of:

a) determining (S101) an ambient noise level;

b) determining in the audio portion (S103, S104, S203) an audio response function corresponding to the determined ambient noise level; and

c) adjusting (S204) the audio response of the audio portion of the radio receiver (10) in accordance with the audio response fimction,

and wherein when the ambient noise level increases to such an extent that the intelligibility of received speech is adversely affected, the determined audio response function serves to increase the gain of high audio frequencies of the audio response relative to the gain of low audio frequencies of the audio response, thereby improving the intelligibility of received speech albeit with a loss of fidelity of a speaker's voice.

2. A method according to claim 1, wherein step (a) is practiced by detecting a volume knob position.

3. A method according to claim 2, wherein step (b) is practiced by accessing an array of audio parameters (S103, S104) and selecting parameters corresponding to the volume knob position.

4. A method according to claim 2, comprising the further step of dividing a receive audio passband into at least low frequency and high frequency sub bands to define an array of audio parameters corresponding to each volume knob position.

5. A method according to claim 4, wherein step (b) is practiced by accessing the array of audio parameters and selecting parameters corresponding to the volume knob position.

6. A method according to claim 1 wherein step (a) is practiced by sampling the ambient noise level using a microphone input (22).

7. A method according to claim 6, wherein step (b) is practiced by accessing an array of audio parameters (S103, S104) and selecting parameters corresponding to the sampled ambient noise level.

8. A method according to claim 6, comprising the further step of dividing a receive audio passband into at least low frequency and high frequency sub bands to define an array of audio parameters corresponding to a range of ambient noise levels.

9. A method according to claim 8, wherein step (b) is practiced by accessing the array of audio parameters (S103, S104) and selecting parameters corresponding to the sampled ambient noise level.

10. A method according to claim 1, wherein step (b) is practiced by building an audio response message (S104) in accordance with the ambient noise level.

11. A method according to claim 10, comprising the further step, prior to step (c), of sending the audio response message (S104) to a digital signal processor (DSP) (20), wherein step (c) is carried out by the DSP.

12. A method according to claim 10, comprising the further step, prior to step (c), of extracting audio response parameters (S203) from the audio response message and substituting the audio response parameters (S204) into a digital signal processor filter routine.

13. A method according to claim 1, wherein step (b) is practiced by modifying a response of a dedicated filter circuit of the audio portion.

14. An apparatus for dynamically altering an audio response of an audio portion (20-28) of a radio receiver (10) whereby to improve the intelligibility of received speech in areas of high ambient noise, the apparatus comprising:

means (22) for determining an ambient noise level;

a controller (12) that builds an audio response message (S104), in accordance with ambient noise level, and

a digital signal processor (DSP) (20) that adjusts (S104) the audio response of the audio portion of the radio receiver in accordance with the audio response message, and wherein when the ambient noise level increases to such an extent that the intelligibility of received speech is adversely affected, the audio response message serves to increase the gain of high audio frequencies of the audio response relative to the gain of low audio frequencies of the audio response, thereby improving the intelligibility of received speech albeit with a loss of fidelity of a speaker's voice.

15. An apparatus according to claim 14, wherein said determining means comprises a detector that detects a volume knob position change.

16. An apparatus according to claim 15, wherein said controller (12) builds said audio response message (S104) by accessing an array of audio parameters (S103) and by selecting parameters corresponding to the volume knob position.

17. An apparatus according to claim 15, wherein said controller (12) divides a receive audio passband into at least low frequency and high frequency sub bands to define an array of audio parameters corresponding to each volume knob position.

18. An apparatus according to claim 17, wherein said controller (12) builds said audio response message by accessing the array of audio parameters (S103) and selecting parameters corresponding to the volume knob position (S104).

19. An apparatus according to claim 14, wherein said determining means comprises a microphone input (22) that samples the ambient noise level.

20. An apparatus according to claim 19, wherein said controller (12) builds said audio response message (S104) by accessing an array of audio parameters (S103) and selecting parameters corresponding to the sampled ambient noise level.

21. An apparatus according to claim 19, wherein said controller (12) divides a receive audio passband into at least low frequency and high frequency sub bands to define an array of audio parameters corresponding to a range of ambient noise levels.

22. An apparatus according to claim 21, wherein said controller (12) builds said audio response message (S104) by accessing the array of audio parameters (S103) and selecting parameters corresponding to the sampled ambient noise level.

23. An apparatus according to claim 14, wherein said DSP (20) extracts audio response parameters (S203) from the audio response message and substitutes the audio response parameters (S204) into a DSP filter routine.

Ansprüche

1. Verfahren zum dynamischen Wechseln einer Audioantwort eines Audioabschnitts (20-28) eines Funkempfängers (10), wodurch die Verständlichkeit empfangener Sprache in Bereich mit hohem Umweltgeräusch verbessert ist, enthaltend die Schritte:

a) Bestimmen (S101) eines Umfeldgeräuschpegels;

b) Bestimmen, in dem Audioabschnitt (S103, S104, S203), einer Audioantwortfunktion gemäß dem bestimmten Umfeldgeräuschpegel; und

c) Angleichen (S204) der Audioantwort für den Audioabschnitt des Funkempfängers (10) in Übereinstimmung mit der Audioansprechfunktion, und wobei

   dann, wenn sich der Umfeldgeräuschpegel in einem solchen Umfang erhöht, dass die Verständlichkeit der empfangenen Sprache ungünstig beeinflusst ist, die bestimmte Audioansprechfunktion zum Erhöhen der Verstärkung der hohen Audiofrequenzen des Audioansprechverhaltens relativ zu der Verstärkung niedrigerer Audiofrequenzen des Audioansprechverhaltens dient, wodurch die Verständlichkeit empfangener Sprache verbessert ist, obgleich ein Verlust der Wiedergabetreue einer Sprache des Sprechers gegeben ist.

2. Verfahren nach Anspruch 1, wobei der Schritt (a) durch Detektieren einer Lautstärkeknopfposition praktiziert wird.

3. Verfahren nach Anspruch 2, wobei der Schritt (b) durch Zugriff auf ein Feld von Audioparametern (S103, S104) und Auswählen von Parametern gemäß der Volumentastenposition praktiziert wird.

4. Verfahren nach Anspruch 2, enthaltend weiter den Schritt zum Unterteilen eines Empfangs-Audiobandbereich in zumindest zwei niederfrequente und hochfrequente Teilbänder zum Definieren eines Felds von Audioparametern gemäß jeder Volumentastenposition.

5. Verfahren nach Anspruch 4, wobei der Schritt (b) durch Zugriff auf das Feld der Audioparameter und Auswählen der Parameter gemäß der Volumentastenposition prakisch umgesetzt wird.

6. Verfahren nach Anspruch 1, wobei der Schritt (a) durch Abtasten des Umfeldgeräuschpegels unter Verwendung einer Mikrofoneingangsgröße (22) praktisch umgesetzt wird.

7. Verfahren nach Anspruch 6, wobei der Schritt (b) praktisch durch Zugriff auf ein Feld von Audioparametern (S103, S104) und durch Auswählen von Parametern gemäß dem abgetasteten Umfeldgeräuschpegel umgesetzt wird.

8. Verfahren nach Anspruch 6, enthaltend ferner den Schritt zum Unterteilen eines Empfangs-Audiofrequenzbereichs in zumindest niederfrequente und hochfrequente Teilbänder zum Definieren eines Felds von Audioparametern gemäß einem Bereich der Umfeldgeräuschpegel.

9. Verfahren nach Anspruch 8, wobei der Schritt (b) praktisch durch Zugriff auf das Feld der Audioparameter (S103, S104) und Auswählen von Parametern gemäß dem abgetasteten Umfeldgeräuschpegel umgesetzt wird.

10. Verfahren nach Anspruch 1, wobei der Schritt (b) durch Aufbauen einer Audio-Antwortmeldung (S104) in Übereinstimmung mit dem Umfeldgeräuschpegel praktisch umgesetzt wird.

11. Verfahren nach Anspruch 10, enthaltend den weiteren Schritt, vor dem Schritt (c), zum Senden der Audio-Antwortmeldung (S104) zu einem Digitalsignalprozesor (DSP) (20), wobei der Schritt (c) durch den DSP ausgeführt wird.

12. Verfahren nach Anspruch 10, enthaltend den weiteren Schritt, vor dem Schritt (c), zum Extrahieren von Audio-Ansprechparametern (S203) aus der Audio-Ansprechmeldung und zum Substituieren der Audio-Ansprechparameter (S204) in eine Digitalsignalprozessor-Filterroutine.

13. Verfahren nach Anspruch 1, wobei der Schritt (b) praktisch durch Modifizieren eines Ansprechverhaltens einer zugewiesenen Filterschaltung für den Audioabschnitt umgesetzt wird.

14. Gerät zum dynamischen Ändern eines Audio-Ansprechverhaltens eines Audioabschnitts (20-28) bei einem Funkempfänger (10), zum Verbessern der Verständlichkeit empfangener Sprache in Bereichen mit hohem Umfeldgeräusch, wobei das Gerät enthält:

eine Vorrichtung (22) zum Bestimmen eines Umfeldgeräuschpegels;

einen Controller (12) zum Aufbauen einer Audio-Ansprechmeldung (S104 in Übereinstimmung mit dem Umfeldgeräuschpegel, und

einen Digitalsignalprozessor (DSP) (20) zum Angleichen (S104) des Audio-Ansprechverhaltens des Audioabschnitts des Funkempfängers in Übereinstimmung mit der Audio-Ansprechmeldung, und wobei dann, wenn der Umfeldgeräuschpegel in einem solchen Umfang erhöht ist, dass die Verständlichkeit der empfangenen Sprache ungünstig beeinflusst ist, die Audio-Ansprechmeldung zum Erhöhen der Verstärkung hoher Audiofrequenzen für das Audio-Ansprechverhalten relativ zu der Verstärkung niedriger Audiofrequenzen für das Audio-Ansprechverhalten dient, wodurch die Verständlichkeit der empfangenen Sprache verbessert ist, obgleich ein Verlust der Wiedergabetreue der Sprache des Sprechers vorliegt.

15. Gerät nach Anspruch 14, wobei die Bestimmungsvorrichtung einen Detektor zum Detektieren einer Volumentastenpositionsänderung enthält.

16. Gerät nach Anspruch 15, wobei der Controller (12) die Audio-Ansprechmeldung (S104) durch Zugriff auf ein Feld von Audioparametern (S103) und durch Auswahl von Parametern gemäß der Volumentastenposition aufbaut.

17. Gerät nach Anspruch 15, wobei der Controller (12) einen Empfangs-Audiofrequenzbereich in zumindest ein niederfrequentes und ein hochfrequentes Teilband unterteilt, zum Definieren eines Felds von Audioparametern gemäß jeder Volumentastenposition.

18. Gerät nach Anspruch 17, wobei der Controller (12) die Audio-Ansprechmeldung aufbaut, durch einen Zugriff auf das Feld der Audioparameter (S103) und durch Auswählen der Parameter gemäß der Volumentastenposition (S104).

19. Gerät nach Anspruch 14, wobei die Bestimmungsvorrichtung eine Mikrofoneingabe (22) zum Abtasten des Umfeldgeräuschpegels enthält.

20. Gerät nach Anspruch 19, wobei der Controller (12) die Audio-Ansprechmeldung (S104) durch einen Zugriff auf ein Feld von Audioparametern (S103) und durch Auswählen von Parametern gemäß dem abgetasteten Umfeldgeräuschpegel aufbaut.

21. Gerät nach Anspruch 19, wobei der Controller (12) den Empfangs-Audiofrequenzbereich in zumindest ein niederfrequentes und ein hochfrequentes Teilband unterteilt, zum Definieren eines Felds von Audioparametern gemäß einem Bereich der Umfeldgeräuschpegel.

22. Gerät nach Anspruch 21, wobei der Controller (12) die Audio-Ansprechmeldung (S104) durch Zugriff auf das Feld der Audioparameter (S103) und durch Auswahl der Parameter gemäß dem abgetasteten Umfeldgeräuschpegel aufbaut.

23. Gerät nach Anspruch 14, wobei der DSP (20) Audio-Ansprechparameter (S203) von der Audio-Ansprechmeldung extrahiert und die Audio-Ansprechparameter (S204) in einer DSP Filterroutine substituiert.

Revendications

1. Procédé de modification dynamique d'une réponse audio d'une partie audio (20-28) d'un récepteur radio (10) au moyen duquel on peut améliorer l'intelligibilité de la parole reçue dans des zones à fort bruit ambiant, comprenant les étapes consistant à :

a) déterminer (S101) un niveau de bruit ambiant ;

b) déterminer dans ladite partie audio (S103, S104, S203) une fonction de réponse audio correspondant au niveau de bruit ambiant déterminé ; et

c) ajuster (S204) la réponse audio de la partie audio du récepteur radio (10) en conformité avec la fonction de réponse audio,
   et dans lequel, lorsque le niveau de bruit ambiant croît de façon telle que l'intelligibilité de la parole reçue est défavorablement affectée, la fonction de réponse audio déterminée sert à augmenter le gain des hautes fréquences audio de la réponse audio par rapport au gain des basses fréquences audio de la réponse audio, afin d'améliorer ainsi l'intelligibilité de la parole reçue au prix d'une perte de fidélité de la voie d'un locuteur.

2. Procédé selon la revendication 1, dans lequel l'étape (a) est mise en oeuvre par détection de la position d'un bouton de volume.

3. Procédé selon la revendication 2, dans lequel l'étape (b) est mise en oeuvre par accès à une table de paramètres audio (S103, S104) et sélection de paramètres correspondant à la position du bouton de volume.

4. Procédé selon la revendication 2, comprenant l'étape supplémentaire consistant à diviser une bande passante audio de réception en au moins deux sous-bandes à basse fréquence et à haute fréquence pour définir une table de paramètres audio correspondant à chaque position du bouton de volume.

5. Procédé selon la revendication 4, dans lequel l'étape (b) est mise en oeuvre en accédant à la table de paramètres audio et en sélectionnant des paramètres correspondant à la position du bouton de volume.

6. Procédé selon la revendication 1, dans lequel l'étape (a) est mise en oeuvre en échantillonnant le niveau de bruit ambiant au moyen d'une entrée de microphone (22).

7. Procédé selon la revendication 6, dans lequel l'étape (b) est mise en oeuvre par accès à une table de paramètres audio (S103, S104) et sélection de paramètres correspondant au niveau de bruit ambiant échantillonné.

8. Procédé selon la revendication 6, comprenant l'étape supplémentaire consistant à diviser une bande passante audio de réception en au moins deux sous-bandes à basse fréquence et à haute fréquence pour définir une table de paramètres audio correspondant à une gamme de niveaux de bruit ambiant.

9. Procédé selon la revendication 8, dans lequel l'étape (b) est mise en oeuvre par accès à la table de paramètres audio (S103, S104) et sélection de paramètres correspondant au niveau de bruit ambiant échantillonné.

10. Procédé selon la revendication 1, dans lequel l'étape (b) est mise en oeuvre par construction d'un message de réponse audio (S104) en conformité avec le niveau de bruit ambiant.

11. Procédé selon la revendication 10, comprenant l'étape supplémentaire, avant l'étape (c), d'envoi du message de réponse audio (S104) à un processeur de signal numérique (DSP) (20), dans lequel l'étape (c) est effectuée par le DSP.

12. Procédé selon la revendication 10, comprenant l'étape supplémentaire, avant l'étape (c), consistant à extraire les paramètres de réponse audio (S203) du message de réponse audio et à introduire les paramètres de réponse audio (S204) dans un sous-programme de filtrage destiné au processeur de signal numérique.

13. Procédé selon la revendication 1, dans lequel l'étape (b) est mise en oeuvre par modification d'une réponse d'un circuit de filtrage spécialisé de la partie audio.

14. Appareil pour modifier dynamiquement la réponse audio d'une partie audio (20-28) d'un récepteur radio (10) afin d'améliorer ainsi l'intelligibilité de la parole reçue dans des zones à fort bruit ambiant, l'appareil comprenant :

un moyen (22) pour déterminer un niveau de bruit ambiant ;

une unité de commande (12) qui construit un message de réponse audio (S104) en conformité avec le niveau de bruit ambiant, et

un processeur de signal numérique (DSP) (20) qui ajuste (S104) la réponse audio de la partie audio du récepteur radio en conformité avec le message de réponse audio, et dans lequel, lorsque le niveau de bruit ambiant croît de façon telle que l'intelligibilité de la parole reçue est défavorablement affectée, le message de réponse audio sert à augmenter le gain des hautes fréquences audio de la réponse audio par rapport au gain des basses fréquences audio de la réponse audio, afin d'améliorer ainsi l'intelligibilité de la parole reçue au prix d'une perte de fidélité de la voie d'un locuteur.

15. Appareil selon la revendication 14, dans lequel ledit moyen de détermination comprend un détecteur qui détecte un changement de position du bouton de volume.

16. Appareil selon la revendication 15, dans lequel ladite unité de commande (12) élabore ledit message de réponse audio (S104) par un accès à une table de paramètres audio (S103) et par sélection de paramètres correspondant à la position du bouton de volume.

17. Appareil selon la revendication 15, dans lequel ladite unité de commande (12) divise une bande passante audio de réception en au moins deux sous-bandes à basse fréquence et à haute fréquence pour définir une table de paramètres audio correspondant à chaque position du bouton de volume.

18. Appareil selon la revendication 17, dans lequel ladite unité de commande (12) élabore ledit message de réponse audio par accès à la table de paramètres audio (S103) et sélection de paramètres correspondant à la position du bouton de volume (S104).

19. Appareil selon la revendication 14, dans lequel ledit moyen de détermination comprend une entrée de microphone (22) qui échantillonne le niveau de bruit ambiant.

20. Appareil selon la revendication 19, dans lequel ladite unité de commande (12) élabore ledit message de réponse audio (S104) par accès à une table de paramètres audio (S103) et sélection de paramètres correspondant au niveau de bruit ambiant échantillonné.

21. Appareil selon la revendication 19, dans lequel ladite unité de commande (12) divise une bande passante audio de réception en au moins deux sous-bandes à basse fréquence et à haute fréquence pour définir une table de paramètres audio correspondant à une gamme de niveaux de bruit ambiant.

22. Appareil selon la revendication 21, dans lequel ladite unité de commande (12) élabore ledit message de réponse audio (S104) par accès à la table de paramètres audio (S103) et sélection de paramètres correspondant au niveau de bruit ambiant échantillonné.

23. Appareil selon la revendication 14, dans lequel ledit DSP (20) extrait des paramètres de réponse audio du message de réponse audio et introduit les paramètres de réponse audio (S204) dans un sous-programme de filtrage du DSP.

Drawing